merge vertices at center bmesh
It's a python type error

Python error is telling you that a type in this line is wrong.  It's getting a list instead of BMVert

Note this piece of code comes from your question and is WRONG

verts=[myarray, myarray1]


since verts is expecting a list of BMVerts (as pointed out in the documentation you linked) without even seeing your code it suggests  myarray, myarray1 are both lists.
Agree with sentiment here to post code

Recommended change

If both myarray, myarray1 are lists of verts sum them  

verts = myarray + myarray1



  I did google for few hours and could not find any usefull help Anyway
  your code gives me the same error verts=[myarray, myarray1] TypeError:
  verts: expected (BMVert), not 'list'
  
  I used your piece of code to combine the variables vertstomerge =
  [verts_start_a, verts_start_b, verts_start_c] Then I did this
  bmesh.ops.remove_doubles(bm, verts=vertstomerge dist=0.001 ) Error
  TypeError: verts: expected (BMVert), not 'list'


No I recommended adding them together.  Could it be that type(verts_start_a) b, c, d is a list?, if it is it will lead to a type error, getting a list, expecting a BMVert.
.

Tip: Search stackoverflow, or google on the cause of errors.  Probably find the solution quicker than writing this question.